Feeder for production of fibers of heatsoftenable materials



Feb. 21;, ROBERSON ETAL 3,305,332 FEEDER FOR PRODUCTION OF FIBERS 0FHEAT-SQFTENABLE MATERIALS Original F iled Dec. 31, 1956 5 s-Sheet 1Marble Roll SW. 51

Cum 1.. ROBE/250M, Nasow J. LEEDY,

A TTORNE Y3 Feb. 21, 1967 Original Filed Dec. 51,

FEEDER FOR PRODUCTION OF FIBERS OF 1. ROBERSON ETAL 3,305,332

HEAT-SOFTENABLE MATERIALS :5 5 Sheets-Sheet 2 Nasou J. New,

Jaws D. RILEY mvmroxs Arronwvs 21, 1957 c. ROBERSON ETAL 3,305,332

FEEDER FOR PRODUCTIQN OF FIBERS OF HEAT-SOFTENABLE MATERIALS OriginalFiled Dec. 31, 1956 5 sheets"shee 5 Cur/s L. Roamsou, Nasmv J. LEEDY,

JAMES A RILEY mmvroxs WYQQ A TTOPIVE Y8 1967v L. ROBERSON ETAL 3,305,332

FEEDER FOR PRODUCTION OF FIBERS 0F HEAT-SOFTENABLVE MATERIALS OriginalFiled Dec. 31, 1956 5 sheets-Sheet 4 ifjl Cur/s L. Rosana/v; g- 9 Nascwd. ZEEDY,

JAM D. lP/LEV IN VEN TORS 21, 1967 c. L. ROBERSON ETAL 3,305,332

FEEDER FOR PRODUCTION OF FIBERS OF- I HEAT-SOFTENABLE MATERIALS 011g1nalFlled Dec. 31, 1956 I 5 sheets-Sheet 5 Curr/s L. Rosana/v, Mason! J[550% Jnnss Q RILEY JNVENTORS ATTORA/EKS United States Patent Office3,305,332 FEEDER FOR PRODUCTION OF FIBERS OF HEAT- SOFTENABLE MATERIALSCletis L. Roberson, Nelson J. Leedy, and James D. Riley, Newark, Ohio,assignors to Owens-Corning Fiberglas Corporation, a corporation ofDelaware Application Oct. 3, 1960, Set. N 0. 60,126, now Patent No.3,104,761, dated Sept. 24, 1963, which is a division of application Ser.No. 631,878, Dec. 31, 1956. Divided and this application Dec. 3, 1962,Ser. No. 241,964

3 Claims. (CI. 65-11) This is a division of our previous application,Serial Number 60,126, filed October 3, 1960, issued as Patent 3,104,761on September 24, 1963, and which was a division of our earlierapplication Serial Number 631,878, filed on December 31, 1956, nowabandoned.

This invention is related to the production of fibers of heat-softenablemineral material and more particularly to a method and means for theproduction of fibers of mineral material wherein desired characteristicsof continuity of operation of the apparatus, and strength properties areimparted to the fibers produced, by providing a plurality of stages ofheat control in the process of formation.

According to the invention as herein described, material in particulateform is heated and melted down into a molten pool and then flowed asstreams from which fibers are attenuated. The mineralmaterials which canbe melted down according to the invention are in the present instanceexemplified by glass which is introduced into a melting unit as marbles.

It is a broad object of the present invention to provide an improvedfiber forming operation in which greater control can be exercised overthe physical properties of the fibers produced.

Another object of the invention is to improve the economy of fiberformation both by way of proper energy utilization and constancy ofoperation to promote elimination of wastage.

In accomplishing these objectives, the melting unit of the inventionincorporates a feeder having a directly associated level control. Thefeeder or bushing also has an electrical current connection arrangementwhich permits control of heat distribution and generation of heataccording to selectable predetermined characteristics. In this respect,the feeder terminal arrangement permits selection of a pattern ofheating of the molten body into which the solid particulate material isintroduced so that the heat utilized is concentrated in the zones wheremost needed.

Furthermore, the particulate form of the material, namely marbles in thepresent instance, are arranged to be preheated and fed to the meltingunit at a regulated rate so that solid material is supplied to themolten pool at a more constant cyclic rate whereby cold spots and theirconsequent tendencies toward an erratic thermal history and unstableflow from the molten body are eliminated.

Further in this regard, the molten material flowed from the melter inthe form of streams is arranged tobe chilled upon emission to improvethe operational continuity of the apparatus and to provide greatercontrol of physical properties of the fibers. In this respect flow froma mass of molten material at extremely high temperatures is limited bysurface tension of the material which tends to block the flow, whereaschilling of the material on emission from a high temperature bodyestablishes a viscosity in the streams which resists surface tension ofthe ma- 3,305,332 Patented Feb. 21, 1967 terial, thereby acting toprevent the formation of droplets and permitting continuous stableattenuation of fibers therefrom.

By incorporation of level controls directly in the feeder of the meltingunit according to the present arrangement, a more exacting static headcontrol is afforded and correspondingly control of temperature of thebody is further made possible. Control of the gradient from the top ofthe molten mass, into which the solidified material is introduced, tothe bottom of the mass from which the streams flow is also madepossible, thereby permitting control of the thermal history of thematerial for desired physical properties in the fibers produced. Suchoperational characteristics are further enhanced by establishingsubstantially fixed rates of introduction and removal of material fromthe molten body to promote stability in the dynamics of thermalconditions of the body.

The foregoing, as well as other objects and features of the invention,will be made more apparent as this description proceeds, especially whenconsidered in connection with the accompanying drawings wherein:

FIGURE 1 is a general layout of fiber forming apparatus partially incross section and partially schematic to illustrate an arrangement ofequipment incorporating the principles of the present invention;

FIGURE 2 is a top plan view of the feeder incorporated in the meltingunit of the apparatus illustrated in FIG- URE 1;

FIGURE 3 is a side elevational view of the feeder of FIGURE 2 showinglevel sensing components in association therewith for maintaining asubstantially fixed level of molten material therein;

FIGURE 4 is an end elevational view of the feeder illustrated in FIGURES2 and 3;

FIGURE 5 is a cross-sectional, side elevational view of a marble hopperand associated feed mechanism for supply of marbles to the melting unitshown in FIG URE 1;

FIGURE 6 is a side elevational view in cross section of a marble feedroll or drum associated with the marble supply hopper of FIGURE 5;

FIGURE 7 is a cutaway plan view of the marble feed roll illustrated inFIGURES 5 and 6;

FIGURE 8 is a schematic diagram of the electrical control circuit forthe apparatus of the invention;

FIGURE 9 is a side elevational view of another feeder adaptable to usein accordance with the principles of the present invention in whichmaterial heating members are located at a relatively high level withinthe feeder;

FIGURE 10 is an end elevational view of the feeder of FIGURE 9;

FIGURE 11 is an end elevational view of still another feeder adaptableto use in accordance with the principles of the present invention havingmaterial heating members located at multiple levels within the feeder;

FIGURE 12 is an end elevational view of another feeder of the inventionin which the lower section in the zone of the orifices is constricted inwidth; and

FIGURE 13 is a side elevational view of still another feeder of theinvention in which circuitous flow channels are provided for materialmelted therein. I

Referring to the drawings in greater detail in which FIGURE 1illustrates an over-all assembly of apparatus in accordance with thepresent invention, wherein a melting unit 10 is arranged to receivemarbles 11 introduced thereto to be melted down within a pool of moltenmaterial 14 contained by a feeder 12.

The molten material 14 flows as streams from orificed 20 having a rotarycollet 22 on which the strand is wound into a package 24 as it istraversed by a suitable traversing device 21 for distribution in thepackage.

The marbles 11 fed to the melting unit are supplied from a marble supplyunit 40 incorporating a marble hopper; 43 and a marble metering drum orroll 41. The metering roll 41 is driven by a motor and speed reducingdrive unit44 connected by way of bevel gears 45 to a shaft-42 on whichthe roll 41-is mounted. Upon controlled rotation of the roll 41 underthe influence of controls more fully described hereinafter, marbles arefed to chutes 46 extending between the feed roll and melting unit 10.The level of the molten body 14 within the melting unit 10 is maintainedconstant by means of levelsensing probes 51 and 52 which areelectrically associated with a control unit 50 which in turn iselectrically connected to the drive unit 44. The assembly is arranged toautomatically supply marbles to the melting unit 10 whenever the levelof the body 14 approaches a low value thereby permitting maintenance ofthe material at a predetermined optimum level.

Referring now more particularly to the feeder or bushing and levelcontrol components, FIGURES 2, 3 and 4 illustrate a feeder 12 of a typeadaptable to operation in a melting unit 10 in accordance with theprinciples of the present invention. The feeder structure is heated byelectrical current passing therethrough and has a material containingportion which holds the material 14 melted therein. The feeder isaccordingly made of a high temperature electrically .conducting materialsuch as platinum or otherprecious metals or alloys having hightemperature resistant properties. The feeder is longitudinal in generalshape and accommodates a plurality of orificed tips in its bottom, suchtips being oriented in aligned relationship across the width of thefeeder. This permits association of shield member with the feeder 10,the

shield members being arranged in extended relation across the under partof the feeder between the rows of tips 15. The structure and operationof the shield members as utilized in the present instance are morefullydescribed in Patent 2,908,036, issued in the name of Robert G. Russellon October 13, 1959. They are spaced, parallelly oriented, longitudinalblade-like members positioned in out-of-contact relation under thefeeder and arranged so as to accommodate a pair of crosswise rows oftips between each adjacent pair. The shield members are cooled bysuitable means such as a header 26 from which they extend (see FIGURE 4)so as to effect absorption of heat energy from the molten glass emittedfrom the tips, thereby forcibly cooling the glass. The shields at thesame time offer protection against disruption in flow by guarding-theflowing streams against air eddies or other extraneous atmosphericdisturbances.

The feeder is of depth such that marbles introduced to the top thereofare fully melted down before reaching thebottom of thefeeder for flowtherefrom. The feeder depth dimension, importantly, is sufficientlygreat to provide a contained volume of molten material large enough thatupon introduction of comparatively cool marbles 11 to themolten mass 14thermal instabilities such as can occur by way of excessive cooling ofthe molten mass and consequently cause disrupting change in viscosity ofthe molten mass, will not occur. To further promote such thermalstability without need for maintenance of an excessively large mass fora given pull rate, and consequently to minimize the feeder size and theamount of precious metal required for the production of fibers at agiven pull rate, an electrically heated foraminous metal web or screenof high temperature, electrically conducting material such as platinumis extended across the interior of the feeder and arranged at levelssuch that it is completely immersed within the molten mass during normaloperation of the equipment. The screen is dimensioned to act as aresistance-type heater which generates heat within the molten body andprovides supplemental heat as needed to completely melt any partiallymelted marbles which may reach the level of the screen. Such marbles,which would otherwise tend to drop to the bottom of the feeder and,possibly disrupt the free flow of material, are instead caught by. thescreen and held at the level thereof until completely melted.

The feeder is made up generally of an assembly of three structuralsections, namely a material containing portion 31, an intermediatesection 38a thereabove, and a cover plate 37 topping the assembly. Thewalls of the structural assembly are suitably dimensioned so thatelectrical current can pass therethrough tosupply heat to materialcontained therein for establishment of a temperature above the meltingpoint of the material.

The material-containing portion 31, beside having the orificed tips 15projecting downwardly on the underside thereof, has a pair of ear-likeelectrical terminals 32 integrally joined to opposite ends of the feederto permit electrical connections to be made therewith by a pair ofwater-cooled terminal clamps 34 which supply electrical current from apower source such as a power transformer (not shown). associated withthe feeder for substantially the full height of the containing section31, thereby permitting selectable positioning of the terminal clamps 34on the terminals and consequent distribution of current through thefeeder in accordance with desired patterns of generation of heat forsupply to the molten mass 14.

34 are in a low level position on the terminals 32, then the ends of thefeeder in the feeding zone are cooled. If the terminal clamps arepositioned at a high level on the terminals 32, then the ends of thefeeding zone reach a higher temperature while heat is correspondinglyremoved more rapidly from the main body of the feeder.

The terminal clamps can also be moved inwardly and outwardly on theterminals to effect a change in heat pattern at the feeder tips. Whenthe center of the feeder is relatively cold compared to the ends, theclamps may be moved outwardly to equalize the temperature across thefeeder zone. correspondingly, when the terminal clamps are movedinwardly on the terminals, the proximity of the cooled clamps to thefeeder ends effects a greater absorption of heat from the ends. By wayof example, for a feeder at a general temperature of2300 F., variationsin temperature in the feeder zone in the order of at least F. can beeffected by the inward and outward adjustment of the terminal clamppositions in this manner.

Metal strips 35 extending from one end to the other along the sides ofthe feeder 12 near the bottom of the container portion 31 act asreinforcement for the feeder bottom. Points 36 centrally located nearthe underside of the feeder where the orificed tips are located areadapted to receive in fixed contact therewith thermocouples formeasurement of the operating temperature of the feeder in the zone ofthe tips. The temperature measured at these points is indicative oftemperature of material emitted from the tips of the feeder.

The screen or web 30 extends downwardly into the material containingportion 31 to form, in a sense, a basket which is supported from pointsbetween the joining seam of the container portion 31 and theintermediate portions 36 of the feeder assembly. Thus, the current Eachterminal 32 is integrally passing through the basket or screen 30 passestherethrough from points above the tops of the terminals 32. In view ofthis fact, the current passing through the screen 30 increases uponpositioning of the terminal clamps 34 in the upper zones of theterminals 32 and conversely is reduced upon lowering of their contactpositions on the terminals. The heat generated within the mass of moltenmaterial 14 by current passage through the screen thus can be selectablyincreased or decreased by changing positions of the terminal clamps 34on the terminals 32. When the marbles introduced into the containerportion do not melt down sufficiently by the time they drop to the lowerlevels of the basket formed by the screen 30, the terminals can beadjusted to a new position in an upper zone of the terminals 32 so thatcurrent passed through the screen will be increased for generation ofmore heat in the upper zone of the feeder.

The cover plate section 37 of the feeder 12 is provided with fouropenings to the interior of the feeder, each of which is surrounded byan upwardly projecting cylindrical stack-like structure. The two outeropenings, having associated stacks 47 are adapted to receive marblesfrom the chutes 46 and in this respect are adaptable to having thechutes connected directly thereto. The two openings are spaced from eachother so that the marbles are introduced generally into the center ofeach of the feeder halves located on opposite sides of its longitudinalcenter.

The two inner openings with their associated stack structures 53 and 54are arranged to receive the sensing probes 51 and 52, respectively. Theprobes are longitudinal needle-like pointed metal rods of hightemperature resistant electrically conducting material such as platinumand are each fixedly mounted concentrically within separate probehousings 58 and 59, respectively. The probes are electrically insulatedfrom their housings by tubes 60 and 61, respectively, made of a hightemperature resistant electrical insulating material, e.g.,

. a refractory material, extending down into the probe housings. Thehousings 58 and 59 are supported in vertically oriented relationship onthe respective shoulders 63 and 64 formed in the stack structures 53 and54. Each of the insulating tubes 60 and 61 project upwardly beyond theirrespective housings and are provided with collars 65 and 66,respectively, adapted to hold electrical terminals 68 and 69 forelectrical connection with the probes 51 and 52, respectively. Theterminals are also arranged to allow vertical position adjustment of theprobes in the upper part of the as such is so electrically connected byway of a connecting wire 67 to the controller 50 that when its extremeend ortip makes contact with the surface of the molten mass 14, a signalis established in the controller so that the drive 44 is maintainedde-energized to withhold supply of marbles to the feeder. When, however,the resistance in the main probe circuit is increased, such as uponbreakage of the contact between the probe and the surface of the moltenmaterial in the feeder, a signal is established in the control unit 50to cause operation of the motor drive 44 for a supply of marbles to thefeeder. v

The second probe 52 is arranged to be a triggering means for an alarm tobe operated when, for some extraneous reason, the molten material 14 inthe feeder drops to an excessively low level. Accordingly, the end ofthe probe 52 is arranged to extend a slight distance deeper in the orderof ,4, to A than the end of the probe 51. Thus, the probe 52 has its endimmersed in the molten mass 14 during all periods of normal operation ofthe feeder. When the level of the material drops below the end of theprobe 52, however, the control unit 50 is arranged to set olf an alarmto indicate to operators that erratic conditions exist in operation ofthe feeder. Suitable audible as well as visual alarm signalling meansare readily associated with the control unit to indicate to operatorswhen corrective measures are necessary.

The ends of the probes 51 and 52 extend to the surface of the moltenmaterial 14 within the bounds of the cylindrical guard walls 55 and 56,respectively, each of which extend from the underside of the cover plate37 to a level a slight distance above the desired level for the moltenbody 14. Partially melted marbles or other extraneous material at thesurface of the molten material are thereby prevented from contacting theprobes and giving chance false level indications. In projecting to alevel just above the surface of the molten material, the walls 55 and 56provide a controlled level environment for the sensing zones bypreventing disturbances at the surface of molten material in the areassurrounding the protected zones from being transmitted to the probes,thus assuring a more accurate sensing of the material level.

FIGURE 8 illustrates the electrical circuitry associated with each ofthe probes 51 and 52 and in this instance the circuit for the main levelprobe 51 is shown. The circuit is designed purposely to operate on asmall current which permits sensitive and exacting control regardless ofthe fact that the molten body being measured becomes part of thecircuit. Only currents of a few microamperes are tolerable in electricalprobe circuits. Large currents it has been found cause swelling orsponging of probe tips. Higher currents and voltages also produce arcingat ,pro'be tips in highly ionized atmospheres. With low currentoperation, the circuit can be adjusted to work on the cone of glassattenuated by probe tips so that actual contact with the glass is neverlost, thereby permitting greater accuracy in the control of levels.

Electrical energy'is supplied to the circuit by way of the transformer80 which has connected in series across its secondary a switching relay86, a cold cathode tube 88, and associated current-limiting resistor 89.The tube 88 when biased with a sutficiently positive voltage applied toits starter anode passes positive pulses of the AC. supplied from thetransformer to effect energization of the relay 86. Energization ofrelay 86 causes its normally closed contacts 86A to be opened, whilede-energization thereof closes contacts 86A to energize the drive unit44 for introduction of marbles 11 into the feeder.

In addition to the branch including tube 88, the transformer secondaryhas bridged thereacross a voltage divider branch made up of a pair ofvseries connected resistances 81 and 82. The feeder 12 with its containedmolten body 14 is connected to the voltage divider through a resistance83, while the other side is connected through the probe 51 and grid ofthe tube 88. A resistance 84 is also connected between the voltagedivider and the starter anode of the tube 88 in parallel with the feederbranch. By this arrangement, the starter anode has a voltage levelestablished by the tap on resistance 82 below the critical value forfiring the tube. Contact of the probe 51 with the glass adds anincrement of in phase voltage sufficient to fire the tube. As long asthe probe 51 makes contact with the molten material 14, the starteranode is maintained sufiiciently positive to permit continued flow ofcurrent through the tube and accordingly to maintain the relay 86energized. When the probe 51 breaks contact with the molten body 14 byreason of the level of the body falling below the predetermined desiredlevel, the bias Voltage supplied to the tube through the resistance 84becomes less positive, stopping the flow of current to the relay andaccordingly closing its contacts 86A to initiate introduction of marbles11 by energizing the marble-supply drive unit 44,

, The circuit associated with the probe 52 is identical to thatdescribed above and operates in a similar manner, except that itprovides an alarm signal when the level of the molten body 14 dropsbelow its lowest safe level.

7 FIGURE 5. illustrates the relationship of the marble metering roll 41within'the marble hopper 43, as well as with its drive 44 and electricalconnection with the controller 50. FIGURES 6 and 7 additionally showdetails of the metering roll illustrating the manner in which marblesare conveyed from the hopper to the chutes 46 leading to the meltingunit 10'. The meteringroll 41 is made up of a cylindrical shell havinghorizontally spaced rows of circumferentially 'aligned marble receivingapertures 71. The shell is fixedly mounted on a shaft '42 for rotationtherewith by spoke members 73 extending from a hub portion fixed to theshaft. On the interior of the shell, and also mounted on the shaft 42,are a pair'of circular disks 72 each aligned directly under one of thecircumferential rows of apertures 71, as illustrated most clearly inFIGURE 7. The diameter of the disks 72, as can be seen in FIGURE 6, issuch that a marble 11 deposited in one of the apertures 71 will rest onthe edge of the disk 72' immediately thereunder'and will be conveyed ina path about thecenter of the shaft 42 as the drum rotatesto a pointwhere the marble wouldbe deposited in an end of the chute 46 such thatthe marble is in effect poured from its aperture upon reaching the endof the chute. If, however, the marbles are either chipped 'or nonunifo'rrn by reason of defects in formation, or for any other reason issmaller than normal size, the clearance between the edge of the disk 72and the interior circumference of the shell of roll 41 is such that thedefective marble will not remain on the edge of the'disk within theaperture, but. instead will drop through the space between the shell andthe disk to the bottom of the roll. The'defective marbles are collectedon the interior of theroll and are moved about the roll interior as itrotates, as shown in FIGURE 6, until each of the broken marbles isdropped through one of the apertures 71. The defective marbles arethusdropped to the bottom'of the m'arble supply unit 40 where they areaccumulated for subsequent removal as waste throughfa trapdoor typeopening 27. By this arrangement, only marbles meeting predetermineddimensional standards of perfection will be deposited in the chutes 46for'transmissi'on to the melting unit 10 thereby assuring introductionof marbles of predetermined tolerances in size and weight.

The metering roll 41 is 'arrangedunder an opening in the bottom of thehopper 43 where the marbles 11 are in effect funneled to the upper sideof the'roll. The surface of the roll is'provided with marble agitatingprojections 74 which are inclined upwardly'to a peakimmediately adjacenta forward edge of each of the apertures 71 so [that upon rotation oftheroll under thehopper,m'arbles a'recaused to align'themselves between theprojections and in the path of the apertures 71 fordepo'sition of onemarble in each of the apertures. By providing the opening in the bottomof the hopper-for an arcuate distance over the circumference ofthe roll41 slightly greater than 90, it has been found thatjd'eposition of amarble in each of the apertures 71 on rotationofthe' roll is assured.The profile of the projections 74' is ar'cuate so'as to prevent jammingof the marbles by sharp edges.

As a' variation of this structural arrangement, the'marble roll surfacecan be provided with continuous ridge-like projections extendingcircumferentially'about the drum on either side of each row of apertures71. With such"an arrangement, the apertures 71 cooperate with the ridgeprojections in functioning as agitators for the marbles to bring them'into alignment for acceptance by the aper- Byway of example, the rate ofrotation of the roll 41 is inthe order of 4 for a fiber production rateof 40 pounds per hour. To reduce the rate of introduction of marbles tothe melting unit for a lower fiber producindicated, each circumferentialrow of apertures :in the roll 41 has associated therewith a separatechute 46. Thus, on rotation of the roll 41, as many marbles areintroduced to the melting unit 10 in each cycle of deposition of marblesin the chutes 46 as there are chutes conmeeting the roll to the meltingunit.

The'marbles in the hopper 43 are funneled to the metering roll 41 bybafiie members 48 and 49 both of which overlap somewhat, but allowpassage of marbles therebetween downwardly to the metering roll. Thebafiles are further arranged to be overhanging structural members whichbear the load of the main mass of marbles in the hopper. Thus, theweight of all the marbles in the hopper is not borne directly by theroll 41, but rather the weight of only a small number of marbles inthehopper are borne ing from the upper portion of the hopper down to alevel below the metering roll through which air may be circulated. Ablower fan 39 is located directly in the channel or air passage 28 andis driven by a motor located exteriorly of the housing. The fanfunctions to force air up through the metering roll 41 and the hopper 43t the upper interior of the housing for circulation downwardly to theunderside of the hopper and subsequent recirculation. A radiant-typeburner '38 is located in the zone under the hopper to heat air whichpasses it and to in turn transfer heat to the marbles on repassage ofthe air upwardly through the hopper. It has been'found that marbles canbe preheated to temperatures in the order of 1000 F. and above bycirculation of heated air in this manner.

Thus, prior to introduction of the mar-bles into the melting unit, theycan be preheated to a value such that considerable reduction can beeffected in the amount of heat absorbed from the molten mass 14 upontheir introduction to this mass. Accordingly, it will be recognized thatthe thermal disturbances effected upon introduction of the marbles tothe molten mass is also minimized.

As a modification of this arrangement, electrical strip heaters can beprovided within the marble hopper, for example, immediately under thebaffles 48 and 49, to supply heat to the marbles in addition to thatsupplied by hot air passage therethrough, or as the sole source of heatfor preheating the marbles.

Now having described the structural details and function of componentsof the assembly, the over-all cooperative operation of components willnow be described. Marbles from the hopper 43 are fed to the meteringroll 41 where marbles which are defective in shape beyond predeterminedtolerances are sorted out by the roll 41 and are discarded as waste. Themore perfect marbles are received and aligned in the roll apertures 41for conveyance forward upon rotation of the roll for transfer of marblesto the chute 46. The roll 41 is rotated only when the level of thematerial in the feeder 12 drops below a pre-set value determined by thesetting of the end of the level sensing probe 51. Contact of the sensingprobe 51 with the molten material establishes a completed circuitthrough the control unit 50 which holds open the power supply circuitfor the drive unit 44. Under these conditions no marbles are fed to thechutes'4-6. When the resistance of contact between the probe and theglass surface increase-s beyond a predetermined magnitude,

such as when the probe end withdraws from the surface of the moltenmaterial and contact is brokenbetween the probe and the molten materialupon drop of the material level, the controller energizes the drive unit44 to cause rotation of the roll 41 thereby depositing marbles into thechutes '46 for transfer to the melting unit 10. Upon a sufficient numberof marbles being deposited in the melting unit, the level rises to avalue which results in closure of the circuit associated with thesensing probe 51. This again results in the drum or roll 41 being halteduntil the next indication is given by the sensing probe that material isneeded by the feeder to re-establish the predetermined desired level. i

If for some reason, the level of the molten material within the feederdrops sufiiciently below that which will maintain contact with bothsensing probes 51 and 53, the control unit is arranged to set off analarm indicating to the operator that the level in the feeder isdangerously low. Corrective measures can then be initiated to introducesufficient material to the feeder to bring the level back up to thedesired height at which the sensing probe 51 remakes contact with thesurface of the material.

Since the mar bles introduced into the melting unit are already heatedupon immersion in the molten mass 14, they do not absorb as much heat toeffect the melting thereof as would otherwise be required if heated fromnormal ambient temperature external of the melting unit. The cooling orlocal chilling by the marbles and generation of incipientdevitrification in the molten mass is thus prevented. Accordingly thequantity of molten material required within the feeder for maintenanceof stable thermal conditions therein is smaller. In addition, preheatingdegasses the marbles in that adsorbed surface gases and moisture aredriven off, thus reducing the possibility of interruptions being causedby occluded gases in the melt. Preheating of marbles also allows themelt to be maintained at a higher temperature for more thorough finingof the glass and more accurate control of its level in addition toreducing the heat work required of the platinum and promoting moreuniform temperature throughout the melt.

The molten mass 14 in the feeder 12 is in a sense divided into two zonesdefined by the screen 30 which extends thereacross generally at a levelapproximately half way below the total depth of the mass. The terminalclamps 34 are so located on the terminals 32 that the heat generated bypassage of current through thescreen 30 is sufiicient to cause thecomplete melt down of the marbles 11 at least by the time they reach thelevel of the screen, thereby preventing a clogging of flow of materialfrom the top zone to the lower zone at the screen. The position of theterminal clamps 34 on the terminals 32 is also such that current passingthrough the walls of the feeder 12 is sufficient to heat the materialcontained therein from the interior wall surfaces toward the center ofthe body of molten material. Theposition of the clamps 34 is thusselected to provide the amount of wall current which will developsufiicient heat in the lower zone to maintain the temperature of themolten mass 14 at a desired value upon emission from the tips 15. Inthis respect, the clamps can be positioned on the terminals 32 forselection of the pattern of current passage through the feedercorresponding to the optimum continuity of material fiow. The terminalclamps thus function with the terminals in a sense somewhat similar to acurrent divider.

Upon emission of molten material from the tips 15, the

cooled shield members 25 absorb heat energy from the fluid cones ofmaterial which form at the orifices to effect a more rapid increase inviscosity of the material, thereby promoting more stable conditions forattenuation of the matter into continuous fibers. By so chilling thecones of material, the surface tension of the material is resisted tothe extent that tendencies toward formation of droplets of the materialis forcibly overcome, thus assuring continuity of attenuation of fibers16 from the feederl By reason of the forceful chilling of the emittedmatter, the temperature of the mass 14 can, in addition, be maintainedat a higher temperature which is assuredly above the devitrificationtemperature of the material, and also at such temperature level that aquick melting of the marbles introduced thereto is effected. The uniformin troduction of marbles at above atmosphere ambient temperature assuresa uniform and non-disruptive thermal cycle for the mass 14, regardlessof the fact that the heat of the mass is utilized to melt down themarbles. F urthermore, close regulation of the level of the molten mass14 assures the presence of a sufiicient quantity of material in thefeeder to effect complete melting of the marbles without fear ofexcessive cooling of the material. In this respect, the level controlscan be said to eliminate thermal channelling and unbalance of thermalconditions from end to end in the feeder.

Thus, over-all controls exist in the assembly to maintain a fixedpattern of introduction of heat energy to the material at each stage inthe process of forming fibers from the marbles so that the thermalhistory of the matter is constantly uniform without the occurrence ofcyclic thermal hunting.

FIGURES 9, 10 and 11 show two alternate types of feeders adaptable tooperation in the assembly of FIG- URE 1 in accordance with theprinciples of the present invention. FIGURES 9 and 10 show a feederconsisting of three sections, namely a main body or containing portion97 having an orificed section 98 joined thereto to form the feederbottom with orificed tips projecting downwardly therefrom and alignedinto a series of adjacent rows. The tip alignment across the width ofthe feeder bottom in pairs of rows, as may be seen in FIG- URE 9,permits ready association of shield members therewith as in the mannerillustrated with the feeder of FIGURES 1 and 3. A cover section 96 forthe feeder is provided with four openings to permit supply of marblesand accommodation of sensing probes in the manner illustrated in thefeeder of FIGURE 3. In this feeder, however, the cross-wise web throughwhich current is passed from the feeder electrical terminals 92 isformed by longitudinal strips extending from one end of the feeder tothe other and supported on cross-wise rods 91 extending from theinterior of one wall to the interior of the opposite wall. The rods 91extend across the feeder interior in positions where the body portion 97is reinforced by vertical metal strips 99 which are intimatelyassociated with the exterior of the feeder.- The position of thecross-wise web of strips 94 is somewhat' below the upper edges of theterminals 92, thereby permitting selection of a position for theterminal clamps on the terminals 92 which will establish the currentflow and heat pattern desired for melting conditions in the feeder. The

'rods 91 and the strips 94 are both made of temperature resisting,electrically conducting material such as platinum with the dimensions ofthe strips 94 being such that the current flow therethrough will resultin generation of heat within the mass in which the web is immersed. Thestrips 94 are flat and are supported on the rods 91 which in turn arespaced sufficiently close that when the temperature of the strips israised to a value for melting the marbles introduced to the top of thefeeder, sufficient bracing exists to prevent sagging thereof. Spacing ofthe strips 94 is close enough to prevent possible passage of solidmaterial therebetween, yet great enough to offer a minimum of resistanceto flow of material through the feeder.

FIGURE 11 illustrates still another feeder adaptable to incorporation inthe assembly of FIGURE 1. In this feeder structure the body or maincontaining portion 108 is capped by a cover section 107 and has anorificed feeding section 109 joined thereunder which has orificed tipsprojecting from the under surface thereof. The ear-like terminals 102extend for a vertical distance corresponding to the vertical dimensionof the body portion 108 similar to the arrangement in the feeder ofFIGURES 9 and 10.

This feeder differs from that of FIGURES 9 and 10 in having more thanone cross-wise web within its interior for supply of heat to the moltenmass contained therein. Four cross-wise webs of resistance heatingmembers are provided in this feeder at different levels spaced generallyequal distances apart extending from the top to the bottom of the bodyportion 108. The top web is formed by metal heating strips 103 whichextend from one end to the other within the feeder and spaced slightlyfrom each other to provide a filtering action for material passedtherethrough, but also having wider gaps formed between the extreme endstrips and side wall of the feeder. The second web, one level below thefirst, is formed by strips 104 similar to those of the topmost level butare staggered so as to have each strip positioned immediately below agap between adjacent strip in the topmost level. This requires a zigzagflow of material passed through the two levels'of heating strips andextends the path through which the material must flow to reach thebottom of the feeder. As a further extension of this concept, the thirdlevel has two plate members 105 extending from one end of the feeder tothe other, both supported on the rods 101 but'spaced from each other sothat the largest space for passage of material through this level existsin the center of the molten mass. The fourth web similarly is made up ofbut a single plate,'but centrally located immediately below the largegap formed below the two plates 105 in the level above. The plate 106 issolid completely across the width of the feeder but is centrally locatedto provide gaps at the side wall zones of the feeder. Thus, moltenmaterial passing from the top of the feeder to the bottom is required totake a Zigzag path upon passag'e'through the first two cross-wise webs,but in passing through the second two webs, the zigzag path is increasedin length, thereby making the length of the path of material approachingthe tip section 107 even greater and promoting the transfer of a greateramount of'heat thereto before emission from the feeder. Correspondingly,the filtering action within the feeder is increased and the possibilityof extraneous material reaching the feeder tips is practicallyeliminated.

FIGURE 12 shows another type of feeder adaptable to incorporation in thepresent arrangement wherein the lower section 118-is smaller incross-sectional area than the upper portion 110. Intermediate the-twolevels, the walls 19 of the feeder are inclined closer together towardthe lower level, thereby providing a feeder in which the molten body ispredominantly heated in the larger'upper portion where, because of itslarger'volume, the molten material is less influenced by introduction ofthe cooler matter to be melted down. Thus, the upper portion of thefeeder acts as a reservoir wherein the colder solid particles have lessinfluence in modification of'thermal conditions within the feeder.Correspondingly, the zone of smaller cross-section in the lower part ofthe feeder which is supplied with material already melted down and Ialready thermally more stable can exert greater'control over temperatureof the material in the zone of emission from the tips' 115, since thevolume over which control is exerted 'is relatively smaller.

The marbles to be melted down in the feeder are introduced through apair of openings 117 on opposite ends of thefeeden'while level detectingprobes are inserted in the probe stacks 113 and 116 centrally located atthe top of the feeder. Electrical connection is made to the feeder bywayof its terminals 112 which extend from the lower portion to the upperportion at each end of the feeder. Heater strips 114 extending from oneend to the other end of the feeder are located in the upperportion,spaced apart from each other across the width of the feeder between thewalls 110.

Still another type of feeder adaptable to use in the ar rangement abovedescribed is shown in FIGURE 13 wherein flow channels 130 are formed byspaced internal walls 131 and 132 which incline upwardly from the endsof the feeder toward the center of the feeder at an upper level. Marblesare introduced to the feeder through openings 127 and are melted in theend compartments formed by the walls 131 prior to ko'w throughforaminou's inlets 128 to the channels 130. The molten material flowsupwardly through the channels 130 to the central area where the channelsgenerally join above a foraminous inlet 129 to a lower central part ofthe feeder.

The material then flows through the inlet 129 to the central part of thefeeder from which it flows through still another foraminous wall section124 extending generally I from one end of the feeder to the other, abovethe lower section containing the orifice tips 125.

A level control probe 126 is centrally disposed at the top of the feederand extends downwardly within the bounds of a cylindrical guard wall 123projecting from the underside of the topof the feeder. The probe isconnected through electrical circuitry to the marble feeder andinitiates supply of marbles as needed in a manner similar to thatexpressed above. The level of the molten material is maintained at aheight such that the foraminous inlet.129 is always below the surface ofthe molten material and such that the compartments at either end of thefeeder into which the solid material is supplied is sufliciently largethat introduction of the marbles thereto will not appreciably effectmodification in temperature of the molten material therein.

In view of the foregoing, it will be recognized that while we have showncertainparticular embodiments of our invention, it will be understoodthat we do not wish to be limited entirely thereto since manymodifications may be made within the concepts of the invention, and we,therefore, contemplate by the appended claims to cover allsuch'modifications as fall within the true spirit and scope of ourinvention.

We claim:

1. A feeder for formation of fibers of heat-softenable materialcomprising a container portion for such material, means for metering ata uniform rate a supply of said material in solid form to said feeder,means for heating said feederto melt said solid material into a moltenpool thereof within said container portion, said feederhaving orificesat the bottom of said container portion through which streams of saidmolten material flow for attenuation into fibers, level controlsassociated with said feeder for establishing a predetermined level ofsaid molten material within saidcontainer portion, said level controlsbeing associated with said supply means in such manner as to supply ametered quantity of said solid material to said feeder upon drop of thelevel of said pool below said predetermined level.

'2. A feeder for formation of fibers of heat-softenable materialcomprising a container portion for such material, means for metering ata uniform rate a supply of said material in solid form to said feeder,means for heating said feeder to melt said solid material into a moltenpool "thereof Within said container portion, said feeder having orificesat the bottom of said container portion through which streams of saidmolten material flow for attenuation into fibers, level controlsassociated with said feeder for establishing. a predetermined level ofsaid molten material within said container portion, said level controlscomprising a probe extending down to a preset maximum level at which theupper surface of said pool is to be maintained, an electrical circuitfor operating said supply means, an auxiliary circuit including saidprobe and pool being so associated with the circuit for said supplymeans that upon break in contact between said probe and pool, the supplymeans is operated to supply a quantity of said solid material sufficientto bring said poolsurface into contact with said probe, at said presetlevel.

3. A feeder for formation of fibers of heat-softenable materialcomprising an electrically conductive longitudinal melting container,electrical terminals for said conta'iner portion disposed at oppositeends of said container, said terminals making electrical engagement withsaid container portion over a distance extending substantially from thetop to the bottom of said container portion, a source of electricalenergy for said feeder, forcibly cooled terminal clamps for connectionto said terminals at any of a number of selectable positions along theheight of 10 said terminals, said terminals also being sufficiently longin extension from said container ends to permit terminal clampconnection at any of a number of selectable positions along the lengthof said terminals thereby permitting connection of said clamps to saidterminals for selec- 15 tion of desired patterns of heat distributionthrough said feeder.

References Cited by the Examiner UNITED STATES PATENTS 1,764,045 6/ 1930Kelleher 13-25 2,692,296 10/ 1954 Piloenc et a1 13-6 2,814,657 11/1957Labino 65-1 3,012,373 12/1961 Willis 651 X 3,028,442 4/ 1962 Glaser 1363,111,550 11/1963 Rushton 13-6 S. LEON BASHORE, Acting Primary Examiner.

DONALL H. SYLVESTER, C. E. VAN HORN, F. W.

MIGA, Assistant Examiners.

1. A FEEDER FOR FORMATION OF FIBERS OF HEAT-SOFTENABLE MATERIALCOMPRISING A CONTAINER PORTION FOR SUCH MATERIAL, MEANS FOR METERING ATA UNIFORM RATE A SUPPLY OF SAID MATERIAL IN SOLID FORM TO SAID FEEDER,MEANS FOR HEATING SAID FEEDER TO MELT SAID SOLID MATERIAL INTO A MOLTENPOOL THEREOF WITHIN SAID CONTAINER PORTION, SAID FEEDER HAVING ORIFICESAT THE BOTTOM OF SAID CONTAINER PORTION THROUGH WHICH STREAMS OF SAIDMOLTEN MATERIAL FLOW FOR ATTENUATION INTO FIBERS, LEVEL CONTROLSASSOCIATED WITH SAID FEEDER FOR